Apparatus for manufacturing optical fiber made of semi-crystalline polymer

ABSTRACT

An extruder heats polymer resin to produce molten polymer and supplies the molten polymer at a constant pressure. A gear pump is in fluid communication with the extruder, receives the molten polymer and controls the polymer flow rate. A spinneret is in fluid communication with the gear pump and spins the molten polymer into the optical fibers. A heater controls the temperature of the optical fibers after the fibers exit the spinneret. The optical fibers are slowly cooled from molten to ambient temperature to eliminate radial morphological variations. A take-up roller tensions the optical fibers after the fibers exit the spinneret to maximize crystallization of the molten polymer.

[0001] This application is a continuation-in-part of U.S. patent application Ser. No. 09/728,447, filed Sep. 15, 2000 and entitled Apparatus for Manufacturing Optical Fiber made of Semi-Crystalline Polymer, which is a continuation-in-part of U.S. patent Application Ser. No. 09/633,308 filed Dec. 15, 2000 and entitled Apparatus for Manufacturing Optical Fiber made of Semi-Crystalline Polymer.

BACKGROUND OF THE INVENTION

[0002] Semi-crystalline polymers have been used to form fibers for textile applications for many years. The physical properties of a fiber is dependent on polymer molecular orientation and structural morphology developed during fiber spinning. The mechanical properties for the fibers are directly related to molecular orientation. Resins with higher molecular weight produce higher strength fibers if processed under the same processing conditions. The higher the degree of orientation the higher the tensile strength for a given fiber. However, the degree of crystallinity and crystalline structure play a very important roll in producing fibers with good dimensional stability. Selecting high molecular weight polyolefin polymers with narrow molecular weight distribution keep the impurities to a minimum. These polymers can easily be extruded and drawn into extremely transparent fibers with controlled morphology. The high molecular weight allows the formation of strong fibers and obtain a very high degree of both amorphous and crystalline orientation. The high degree of crystallinity obtained by using such polymer provides dimensional stability that cannot be obtained using amorphous polymers.

[0003] Since polyolefins melt at low temperatures, extruding and processing of these polymers requires minimum energy as compared to all other polymers. For example, glass melts at 1200 C. and other amorphous polymers melt at much higher temperatures as compared to polyolefins. Therefore, it is much cheaper to produce optical fibers from polyolefin semi-crystalline fibers than those from glass and other amorphous polymers. These fibers are much lighter due to their inherent low densities and have excellent flexibility for handling. Glass fibers are simply too heavy and too fragile for handling and they require sophisticated claddings and end-to-end attachment devices.

[0004] In the manufacture of synthetic fibers including polypropylene, nylon and polyester, molten polymer is extruded through small holes to form filaments which are drawn down and solidified on rotating rolls. In a second stage the solidified filaments are passed from a slow roll to a fast roll drawing them down several times in diameter. The filaments formation process is known as melt spinning, the solid state stretching process as drawing.

[0005] It has been well established in the melt spinning process that polymer melts are converted to uniaxially oriented filaments. The orientation in melt spun filaments has been investigated by various researchers using wide angle x-ray scattering (WAXS), birefringence and small angle x-ray scattering (SAXS). Generally molecular orientation has been expressed in terms of Hermans-Stein orientation factors, with WAXS being applied to crystalline orientation and birefringence to detect amorphous orientation [Kitao, T, Yamada, K, Yamazaki, T, Ohya S.: Sen-i-Gakkashi, 28, p. 61 (1972); Kitao, T,. Ohya, S., Furukawa, J, Yamashita, S.: J. Polym. Sci. Polym. Phys. 11, p. 1091 (1973); Abbott, L. E., White, J. L.: Appl. Polym. Symp. 20, p. 247 (1973); Dees, J. R., Spruiell, J. E.: J. Appl. Polym. Sci. 18, p. 1055 (1974); Spruiell, J. E., White, J. L.: Polym. Enj. Sci. 15, p. 660 (1975); Nadella, H. P., Henson, H. M., Spruiell, J. E., White, J. L.: J. Appl. Polym. Sci. 21, p. 3003 (1977); Bankar, V. G., Spruiell, J. E., White, J. L.: J. Appl. Polym. Sci. 21, p. 2341 (1977); Shimizu, J, Toriumi, K, Imai, Y.: Sen-i-Gakkashi 33, p. T-255 (1977); Danford, M. D., Spruiell, J. E., White, J. L.: J. Appl. Polym. Sci. 22, p. 3351 (1978); Heuvel, H. M., Huisman, R.: J. Appl. Polym. Sci. 22, p. 2229 (1978)]. This orientation is found to be a unique function of the spinline stress. For the case of polyolefins WAXS has generally detected a lamellar structure which at high spinline stresses is oriented perpendicular to the fiber axis [Dees, J. R., Spruiell, J. E.: J. Appl. Polym. Sci. 18, p. 1055 (1974); Spruiell, J. E., White, J. L.: Polym. Enj. Sci. 15, p. 660 (1975); Nadella, H. P., Henson, H. M., Spruiell, J. E., White, J. L.: J. Appl. Polym. Sci. 21, p. 3003 (1977); Katayama, K, Amano, T., Nakamura, K: Koll Z-Z Polym. 226, p. 125 (1967); Noether, H. D., Whitney, W.: Koll Z-Z Polym. 251, p. 991 (1973); Sprague, B. S., Macromol, J.: Sci. Phys. B8, p. 157 (1973)]. From the work of Keller and Machin [Keller, A., Machin, M. J: J. Macromol. Sci. Phys. B1, p. 41 (1967)], Dees and Spruiell [Dees, J. R., Spruiell, J. E.: J. Appl. Polym. Sci. 18, p. 1055 (1974)] and later investigators it is generally hypothesized that the structure observed by SAXS and WAXS consists of folded chain lamellae. These lamellae are arranged in aggregates to form a spherulitic superstructure when melt spinning is carried out at low spinline stresses but at higher spinning stresses they nucleate along lines parallel to the filament axes and grow radially outward to form a so called “row structure” or cylindrite morphology.

[0006] In the drawing process, filaments first exhibit local necking but they eventually become uniform at a point known as the natural draw ratio. The necked regions and drawn out filaments exhibit significantly increased levels of polymer chain orientation [Fankuchen, I., Mark, H.: J. Appl. Phys. 15, p. 364 (1944); Wyckoff, H. W.: J. Polym. Sci. 62, p. 83 (1962); Kasai, N., Kakudo, M.: J. Polym. Sci., pt. A2, p. 1955 (1961); Samuels, R. J.: J. Polym. Sci. A-26, p. 2021 (1968); White, J. L., Dharod, K. C., Clark, E. S.: J. Appl. Polym. Sci. 18, p. 2539 (1974); Sze, G. M., Spruiell, J. E., White, J. L.: J. Appl. Polym. Sci. 20, p. 1823 (1976); Nadella, H. P., Spruiell, J. E., White, J. L.: J. Appl. Polym. Sci. 22, p. 3121 (1978); Kitao, T., Spruiell, J. E., white, J. L.: Polym. Eng.Sci. 19, p. 761 (1979)]. Another phenomenon occurring during the drawing process is the development of fibrillation which transforms the initially solid homogenous filament into a non-homogenous structure containing many “fibrils” together with elongated voids [Samuels, R. J.: J. Polym. Sci. A-26, p. 2021 (1968); White, J. L., Dharod, KC., Clark, E. S.: J. Appl. Polym. Sci. 18, p. 2539 (1974); Sze, G. M., Spruiell, J. E., White, J. L.: J. Appl. Polym. Sci. 20, p. 1823 (1976); Nadella, H. P., Spruiell, J. E., White, J. L.: J. Appl. Polym. Sci. 22, p. 3121 (1978); Kitao, T, Spruiell, J. E., White, J. L.: Polym. Eng.Sci. 19, p. 761 (1979); Statton, W. O.: J. Polym. Sci. 41, p. 143; Sakaoku, K, Peterline, A: J. Polym. Sci. A-29, p. 895 (1974); Glenz, W, Morossoff N., Peterlin, A.: Polymer Letters 9, p. 211 (1971); Muzzy, J. E., Hansen, D.: Textile Res. J. 41, p. 436 (1971); Vonk, C. G.: Colloid Polym. Sci. 257, p. 1021 (1979)]. It is this problem and its interaction with melt spinning that is a concern. In general, observations of fibrillation have been qualitative in character, with authors noting the existence of this phenomenon, and sometimes hypothesizing mechanisms [Sakaoku, K, Peterline, A: J. Polym. Sci. A-29, p. 895 (1971); Peterlin, A.: J. Polym. Sci. 9, p. 61 (1965)]. Investigations [Sze, G. M., Spruiell, J. E., White, J. L.: J. Appl. Polym. Sci. 20, p. 1823 (1976); Kitao, T, Spruiell, J. E., White, J. L.: Polym. Eng.Sci. 19, p. 761 (1979)] using SAXS and scanning electron microscopy (SEM) have indicated that in high density polyethylene and polypropylene fibrillation tends to increase with draw ratio and decrease with increasing draw temperature.

SUMMARY OF THE INVENTION

[0007] The present invention is an apparatus for manufacturing optical fiber made of semi-crystalline polymers. The apparatus includes: An extruder heats polymer resin to produce molten polymer and supplies the molten polymer at a constant pressure. A gear pump is in fluid communication with the extruder, receives the molten polymer and controls the polymer flow rate. A spinneret is in fluid communication with the gear pump and spins the molten polymer into the optical fibers. A heater controls the temperature of the optical fibers after the fibers exit the spinneret. The optical fibers are slowly cooled from molten to ambient temperature to eliminate radial morphological variations. A take-up roller tensions the optical fibers after the fibers exit the spinneret to maximize crystallization of the molten polymer.

[0008] The fibrillation and void development during drawing of melt spun polypropylene filaments is also shown. The filament orientation was characterized by wide angle x-ray scattering and birefringence. Crystallinity was determined by the DSC technique. The development of fibrillated superstructure was followed by SEM, and the void structure was studied by SAXS. Void fractions were also estimated through a combination of density and crystallinity measurements. The following conclusions were reached:

[0009] 1) The usual changes in orientation were observed. Orientation increased with take up velocity during melt spinning, polymer molecular weight and draw ratio. Orientation decreased slightly with increasing draw temperature.

[0010] 2) Crystallinity increased with increasing draw ratio and draw temperature but was not much affected by molecular weight in the range studied.

[0011] 3) Qualitative observation of the level of fibrillation by SEM photomicrographs indicated that fibrillation is very extensive after drawing at 25° C. Fibrillation decreases with increasing draw temperature, but it increases with increasing draw ratio and polymer molecular weight. Filaments spun with low take up velocity (and spin orientation) fibrillate less comparatively than those spun with higher take-up velocity.

[0012] 4) The volume fraction of microvoids ranged from about 0.0004 to 0.028 (0.04 to 2.8%).

[0013] 5) The volume fraction of microvoids computed from the SAXS technique was found to correlate quite well with microvoid fractions estimated from a combination of crystallinity (DSC technique) and density measurements.

[0014] 6) The volume fraction of microvoids increased with

[0015] a) increased draw ratio,

[0016] b) decrease of draw temperature,

[0017] c) increased molecular weight,

[0018] d) increase of take-up velocity during melt spinning.

[0019] 7) The Guinier analysis showed that the average void size had dimensions of 25 to 40 nm parallel to the fiber axis and of order 15 to 30 nm perpendicular to the fiber axis. The average void size increased with increase in draw temperature and decrease of molecular weight, but was not a strong function of draw ratio or spin orientation.

[0020] 8) The void number density increased with decrease of draw temperature, and with an increase of draw ratio, molecular weight and spin orientation.

[0021] 9) The fiber direction mechanical properties tend to correlate with the orientation developed and were not substantially a function of fibrillation or void fraction per se.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 is a schematic view of a first embodiment of the apparatus of the present invention;

[0023]FIG. 2 is a schematic view of a second embodiment of the apparatus of the present invention;

[0024]FIG. 3A is a cross-sectional view of a spinneret of the present invention;

[0025]FIG. 3B is an end view of a spinneret of the present invention;

[0026]FIG. 4 is a first attenuation graph of the fiber of the present invention;

[0027]FIG. 5 is a second attenuation graph of the fiber of the present invention;

[0028]FIG. 6 is a close-up of FIG. 5 at 850 nm;

[0029]FIG. 7 is a close-up of FIG. 5 at 1310 nm;

[0030]FIG. 8 is an attenuation graph of the fiber of Table 5;

[0031]FIG. 9 is an attenuation graph of the fiber of Table 6;

[0032]FIG. 10 is an attenuation graph of the fiber of Table 7;

[0033]FIG. 11 is an attenuation graph of the fiber of Table 8;

[0034]FIG. 12 is an attenuation graph of the fiber of Table 9;

[0035]FIG. 13 is an attenuation graph of the fiber of Table 10;

[0036]FIG. 14 is an attenuation graph of the fiber of Table 11;

[0037]FIG. 15 is an attenuation graph of the fiber of Table 12;

[0038]FIG. 16 is an attenuation graph of the fiber of Table 13;

[0039]FIG. 17 is an attenuation graph of the fiber of Table 14; and

[0040]FIG. 18 is an attenuation graph of the fiber of Table 15.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] 1 Apparatus and Materials

[0042] The present invention employs semi-crystalline homopolymer resins instead of inorganic glass, amorphous, or other copolymers as raw materials. This will give the following advantages compared to glass and other presently used resins.

[0043] First, less impurity is present due to selecting high molecular weight polymers with very narrow molecular weight distribution and minimized processing additives. Polyethylene resin contains only a very minute amount of antioxidant, which is less than 600 PPM. Antioxidants are used to prevent thermal degradation during processing, as even trace amounts of metals and other impurities on the resins should be avoided. Outgassing for this resin is under 14 PPM and polydispersity of less than 4. Such narrow molecular weight distribution is the most crucial factor in order to eliminate radial morphological variations due to the influence of shear at the die wall before extrudate exits the die as well as formation of the fiber final structure. High-density, high molecular weight polyolefin, resins with molecular weight ranging from 50,000-300,000 and polydispersity of <3 are the most desired materials. Other semi-crystalline homopolymers such as polypropylene, isotactic polystyrene, polyethylene oxide, polyoxymethylene, nylons (such as, for example, nylon 6066), polyvinlidene fluoride and alike can also be used to form advance fibers for such optical applications. Since the degree of crystallinity for these resins are not as high as those of polyethylene resins, we will incorporate up to 5% clearing agents during polymerization in order to form small crystals of controlled structure and eliminate undesired density variations within the formed fibers. By “semi-crystalline” it is meant that the final fiber product produced by the teaching herein has from about 30% to about 99% crystallinity.

[0044] Second, semi-crystalline resins are very easy to process and can be formed into pure fibers at much lower processing temperatures (lower energy costs during production) as compared to glass and amorphous polymers. They have lower density therefore are much lighter than glass and easier to handle.

[0045] Fiber spinning is performed by two different methods. These are traditional spinning and high speed spinning. Traditional spinning is done in two separate steps. First, fibers are immediately cooled or quenched into a water bath and then are collected as spun fibers. These fibers then are drawn in a second step of the process. In high speed spinning process, fibers are made in a single step from the initial resin into final drawn fibers.

[0046] It is well known in the art that the conventional two step spinning and drawing method always produce fibers with a higher degree of both amorphous and crystalline orientation. In contrast, less quality fibers are produced with high speed spinning, since the mechanical drawing step is missing. However, the production rate is much higher for the high-speed spinning as compared to conventional fiber spinning. Although highly oriented and very strong fibers are produced by such methods, structural variations within the fibers have not been eliminated. In contrast, the subject invention produces engineered fibers with controlled structural morphology having a maximum degree of both crystalline and amorphous orientations.

[0047] The present invention precisely controls morphological variations developed during the spinning of fibers and incorporates the stepwise drawing procedure into the fiber spinning line to produce the optical fibers in one effective procedure and in a continuous manner. This invention eliminates incomplete crystallization which can occur during spinning under low tension, transforms the spherulitic morphology into lamellae crystals, and removes all microvoids and other morphological defects within the fibers. The above is accomplished in the present invention by precisely controlling both temperature and tension during the fiber formation process. Temperature is controlled by providing heating zones around key components during fiber manufacture, such as the extruder and the spinneret. Additionally, an air heater provides warm air to the point of egress of the molten filaments from the spinneret, this area preferably surrounded by a porous skirt in order to allow slow, controlled cooling of the fibers from molten to ambient.

[0048] Tension is controlled by a plurality of take up rollers and tension rolls that pass the cooling fibers in an unwound state between the requisite processing stations.

[0049] A first embodiment of the apparatus of the present invention is shown in FIG. 1. Special polymer resins mentioned above are added into the hopper 101 of an extruder 103. The extruder supplies the molten polymer to a gear pump 105 at a constant pressure at, for example, between about 50 barr and about 250 barr, and preferably about 200 barr. A precision gear pump 105 is used to provide a constant polymer flow rate to the spinneret 107.

[0050] The spin pump 105 is a positive displacement, four steam gear pump with hydraulic splits, and provides a constant flow rate of polymer through the spinneret 107 of, for example, between about 0.01 cubic centimeter/revolution and about 3 ccm/rev., and preferably about 1.2 ccm/rev. This pump 105 is very crucial so that any flow rate variations be eliminated in order to have linear density along the filaments, and subsequently along the tow.

[0051] As filaments 109 emerge from the spinneret 107, they are accelerated (at, for example, between about 200 meter/min. and about 600 m/min., and preferably about 500 m/min.) away from the outlet, allowing stretching to occur while the polymer is still molten. A transverse air stream heated by air heater 112 and communicating with skirt 111, preferably a chamber having an ingress and egress through which filaments 109 pass, then slowly cools the stretched, semi-molten filaments. More specifically, air heater 112 passes warm air, by means of a blower, to skirt 111. The air from air heater 111 is of a temperature between the temperature of the molten filaments and the ambient air temperature, for example, between about 20° C. and about 120° C., and preferably about 100° C. The air is blown from air heater 112 at a speed of, for example, between about 5 cubic feet/min. and about 100 cft./min., and preferably about 50 cft./min. While only one air heater 112 and skirt 111 are shown, the subject invention contemplates one or more air heaters 112 and skirts 111 forming one or more temperature zones, with each temperature zone having a temperature gradient lower than the preceding temperature zone, through which the filaments 109 pass to control their cooling. The speed and temperature of the air stream from air heater 112 is controlled to help ensure uniformity along the filaments. One to ten meters below the spinneret, these filaments 109 are brought together and passed, un-wound onto take up godets 113. Uniform speed of godets 113 is critical to the filament speed and structural uniformity. The speed of the godets 113 determines the tension in the thread line, the speed of godets 113 being, for example, between about 220 meter/min. and about 660 m/min., and preferably about 550 m/min., to achieve tension of, for example, about 10 percent. Drawing of fibers is a stretching process, which increases the strength of the filaments by increasing the orientation of the polymer molecules to the parallel axis of the filaments. Drawing in the solid state is much more effective at producing orientation of the molecules than the stretching which occurred in the molten state during extrusion like high speed spinning.

[0052] At this stage, the tow of filaments 109 is transferred via two feed rolls into the first zone hot drawing oven 115. In this first drawing step the filaments are stretched at a temperature above the glass transition temperature, and below the melting temperature. In the first drawing step, the draw ratio is, for example, between about 1 and about 3, and is preferably about 2, while the temperature is, for example, between about 250° C. and about 110° C., and is preferably about 100° C. Drawn filaments are stretched further through the second drawing zone 117 at elevated temperatures and eventually annealed at station 119 under tension to perfect and freeze the final fiber structure. In the second drawing step, the draw ratio is, for example, between about 2 and about 20, and is preferably about 12, while the temperature is, for example, between about 90° C. and about 155° C., and is preferably about 150° C. The fibers are annealed under tension at between about 90° C. and 155° C., and preferably about 150° C. The fibers then are wound automatically and packaged for shipment at station 121.

[0053] There are several heating zones 123, preferably being electrically controlled heating units and associated blowers or fans within an enclosure, which maintain the desired temperatures around the extruder 103 and the spinning head 107. Unlike conventional spinning, as the molten filaments are exiting the die, warm air is applied simultaneously around the fibers by heater 112 to cool them uniformly in order to eliminate radial morphological variations. As stated above, these fibers are then carefully solidified by godet or take up roll 113 under high spinning stress in order to maximize crystallization, and are drawn down on a feed role rotating at the desired take-up speed. At this point the filaments are transferred under higher tension from tension roll 114 through the first hot air drawing station 115, where a natural draw ratio of up to seven times is applied. This will remove all the necks and transforms the spherulitic crystals into lamellae morphology. These fibers then, under high tension from tension roll 116, enter the second drawing station 117 where they are continuously drawn at maximum draw ratios and at much higher drawing temperatures. At this stage, resultant fibers exhibit a very high c-axis orientation of the polymer crystals (extended chain morphology at the core region of the fibers, which is perfectly crystalline) and are surrounded by a sheath with a two phase morphology of altering crystalline and amorphous regions having a high degree of both amorphous and crystalline orientation. These fully oriented fibers then pass through the final heat setting station 119 under tension from tension roll 118 to secure their crystallization as well as to remove all other impurities. One example of these impurities is extremely small voids, ranging in size from one to several hundred angstrom, that may still exist within the structure of these fully oriented fibers. Incomplete crystallization is prevented, as is impurity formation, during spinning and drawing by the present invention. Finally, the fibers are wound at take-up station 121, which includes a windup bobbin 125.

[0054] Fibers drawn by this invention at drawing temperatures close to their melting points will be extremely transparent at the core and have highly extended crystalline structures. Such fibers exhibit a high degree of C-Axis crystalline orientation, which contribute extensively to a higher transmission rate as well as reduction in the attenuation loss. In addition, such highly crystalline fibers will have a very high tenacity ranging from 5-14 g/denier. Tenacity for glass fiber is from 5-8 g/denier. Percent elongation to break for semi-crystalline fibers of this invention ranges from 5%-500%. Glass fibers have percent elongation to break from 1%-25%. High degree of crystallinity for fibers of this invention prevents any molecular shrinkage within these fibers. As a result, excellent dimensional stability is expected from such fibers when used under different environmental conditions. Since these semi-crystalline fibers have excellent ductility they are easier to handle and can be bent without fractures. They can be produced almost endless due to their unique radius of curvature and need less number of terminals in long distance applications. They can also be easily connected to light source or other fibers.

[0055] The second embodiment of the present invention is shown in FIG. 2. The second embodiment of FIG. 2 shares many of the same components of the first embodiment of FIG. 1, and like components in these two embodiments are described above regarding FIG. 1 and share like element numbers. Similarly, all of the pressure, speed, temperature and draw ratio parameters of FIG. 1 apply to FIG. 2. Unlike the embodiment of FIG. 1, the embodiment of FIG. 2 facilitates the manufacture of fibers having an outer sheath of a first polymer, and an inner core section of a second polymer. Alternatively, the inner core section can be hollow, instead of being comprised of a second polymer. When the inner core section is hollow, it may contain air (which transmits light better than a solid polymer in the inner core section), a vacuum, or a gas (for example, nitrogen or helium) that facilitates light transmission better than air. Note that when the fiber is hollow, fiber costs are lower than in a solid fiber. Additionally, when the fiber of the present invention has an outer sheath of a first polymer, cladding is not required.

[0056] In order to produce a fiber having an outer sheath of a first polymer and an inner core section of a second polymer, two hoppers 101A and 101B each feed extruders 103A and 103B, respectively. Gear pumps 105A and 105B communicate with extruders 103A and 103B, respectively. Gear pumps 105A and 105B are in fluid communication with spinneret 107. Spinneret 107 has a unique configuration (shown in FIGS. 3A and 3B) that allows the polymer (or gas) from hopper 101A, extruder 103A and gear pump 105A to be enrobed by the polymer from hopper 101B, extruder 103A and gear pump 105A. More specifically, spinneret 107 has a single orifice 301, as shown in FIGS. 3A and 3B, through which a first polymer and a second polymer are sequentially passed to form a fiber having an outer sheath of a first polymer and an inner core of a second polymer. Spinneret 107 may be a spinneret manufactured by Fourné Polymertechnik of Germany and can have one, or more than one, orifices. The formed filament then undergoes processing as described in the first embodiment of FIG. 1 starting at take-up roll 113 of FIG. 1 and continuing through all stations to take-up station 121 of FIG. 1. When air or a gas, instead of a polymer, fills the inner core section of the fiber, hopper 101A, extruder 103A and gear pump 105A are replaced by air/gas source 109. Air gas source 201 is thus in fluid communication with spinneret 107.

[0057] Next referring to a third embodiment of the present invention, this embodiment encompasses the temperature control protocol of the first embodiment of the present invention, with the tension control protocol being optionally employed in a continuous manner, or in a non-continuous fashion at a later time and/or local, or not being employed at all. For this third embodiment of the apparatus of the present invention, reference is again made to FIG. 1, and the pressure, speed, temperature and draw ratio parameters of FIG. 1 apply to the third embodiment.

[0058] Special polymer resins mentioned above are added into the hopper 101 of an extruder 103. The extruder supplies the molten polymer to a gear pump 105 at a constant pressure. A precision gear pump 105 is used to provide a constant polymer flow rate to the spinneret 107.

[0059] The spin pump 105 is a positive displacement, gear pump, and provides a constant flow rate of polymer through the spinneret 107. This pump 105 is very crucial so that any flow rate variations be eliminated in order to have linear density along the filaments, and subsequently along the tow.

[0060] As filaments 109 emerge from the spinneret 107, they are accelerated away from the outlet, allowing stretching to occur while the polymer is still molten. A transverse air stream heated by air heater 112 and communicating with skirt 111, preferably a chamber having an ingress and egress through which filaments 109 pass, then slowly cools the stretched, semi-molten filaments. More specifically, air heater 112 passes warm air, by means of a blower, to skirt 111. The air from air heater 111 is of a temperature between the temperature of the molten filaments and the ambient air temperature. While only one air heater 112 and skirt 111 are shown, the subject invention contemplates one or more air heaters 112 and skirts 111 forming one or more temperature zones, with each temperature zone having a temperature gradient lower than the preceding temperature zone, through which the filaments 109 pass to control their cooling. This cooling can also be performed in one or more hot water baths, as opposed to air chambers. The speed and temperature of the air stream from air heater 112 is controlled to help ensure uniformity along the filaments.

[0061] There are several heating zones 123, preferably being electrically controlled heating units and associated blowers or fans within an enclosure, which maintain the desired temperatures around the extruder 103 and the spinning head 107. Unlike conventional spinning, as the molten filaments are exiting the die, warm air and/or warm water is applied simultaneously around the fibers by heater 112 to cool them uniformly in order to eliminate radial morphological variations. As stated above, in this third embodiment of the present invention, the fibers may or may not next proceed to controlled tension processing stations as described in the first embodiment, either immediately or after passage of time.

[0062] A fourth embodiment of the present invention encompassing the tension control protocol is next described, either with or without the temperature control process of the first embodiment of the present invention; and if with, either immediately thereafter or after passage of time (i.e. continuous or non-continuous). Again, the pressure, speed, temperature and draw ratio parameters of FIG. 1 apply to this fourth embodiment. Referring to FIG. 1, filaments previously processed either with or without the controlled temperature protocol of the first embodiment of the present invention are brought together and passed onto take up godets 113. Uniform speed of godets 113 is critical to the filament speed and structural uniformity. The speed of the godets 113 determines the tension in the thread line. Drawing of fibers is a stretching process, which increases the strength of the filaments by increasing the orientation of the polymer molecules to the parallel axis of the filaments. Drawing in the solid state is much more effective at producing orientation of the molecules than the stretching which occurred in the molten state during extrusion like high speed spinning.

[0063] At this stage, the tow of filaments 109 is transferred via two feed rolls into the first zone hot drawing oven 115. In this first drawing step the filaments are stretched at a temperature above the glass transition temperature, and below the melting temperature. Drawn filaments are stretched further through the second drawing zone 117 at elevated temperatures and eventually annealed at station 119 under tension to perfect and freeze the final fiber structure. The fibers then are wound automatically and packaged for shipment at station 121.

[0064] As stated above, these fibers are then carefully solidified by godet or take up roll 113 under high spinning stress in order to maximize crystallization, and are drawn down on a feed role rotating at the desired take-up speed. At this point the filaments are transferred under higher tension from tension roll 114 through the first hot air drawing station 115, where a natural draw ratio of up to seven times is applied. This will remove all the necks and transforms the spherulitic crystals into lamellae morphology. These fibers then, under high tension from tension roll 116, enter the second drawing station 117 where they are continuously drawn at maximum draw ratios and at much higher drawing temperatures. At this stage, resultant fibers exhibit a very high c-axis orientation of the polymer crystals (extended chain morphology at the core region of the fibers, which is perfectly crystalline) and are surrounded by a sheath with a two phase morphology of altering crystalline and amorphous regions having a high degree of both amorphous and crystalline orientation. These fully oriented fibers then pass through the final heat setting station 119 under tension from tension roll 118 to secure their crystallization as well as to remove all other impurities. One example of these impurities is extremely small voids, ranging in size from one to several hundred angstrom, that may still exist within the structure of these filly oriented fibers. Incomplete crystallization is prevented, as is impurity formation, during spinning and drawing by the present invention. Finally, the fibers are wound at take-up station 121, which includes a windup bobbin 125. As stated above, in this fourth embodiment of the present invention, the fibers may or may not have been, either immediately or after passage of time, first processed with the temperature control protocol of the first embodiment of the present invention.

[0065] Non-limiting examples of extrusion conditions are shown below in Table 1. TABLE 1 Material Spinneret Static mixer Polypropylen Spin finish ø 0.3/0.5/0.65/0.8  100 u Without Temp. dryer Spin date Pump Speeds Temperatures Winder Run Juni 2000 (rpm) Pressure (20 C. Godets (°) Quench Time Spin Sam- Spin Spin (bar) Extruder Melt Spin (m/min) (m/min) (DH/min) Helix (Pa) (° C.) Start- Re. date ple Doff Extr 1 1 P₁ P₂ P₄ ZI ZII ZIII MH MH_(m) pipe head 1 2 Wind Wobb Ang. P₅ Temp Finish ( ) 06/27 1 1 57.5 12.8 12.5 75 200 48.5 225 250 260 262 259.7 260 260.0 260 260 250 400 0 (1.4) 1 2 57.5 12.8 12.5 75 200 48.5 225 250 260 262 259.7 260 260.0 250 250 250 400 z.T. (1) 1 3 57.5 12.8 12.5 75 200 48.5 225 250 260 262 259.7 260 260.0 250 250 250 400 75 21 (1) 1 4 57.5 12.8 12.5 75 200 48.5 225 250 260 262 259.7 260 260.0 250 250 250 400 75 21 (2) 06/28 1 5 57.5 12.8 12.5 75 200 48.5 225 250 260 262 259.7 260 260.0 250 250 250 400 75 21 (3) 1 6 57.5 12.8 12.5 75 200 48.5 225 250 260 262 259.7 260 260.0 250 250 250 400 75 21 1 7 with hot godets no goog running 75 21 (2) 6 1 225 250 252 252 251.4 252 252.0 250 250 250 400 75 21 (2) 2 225 245 245 245 244.8 245 243.0 250 250 250 400 75 21 (2) 06/29 1 53.0 25.0  0.0 75 190 37.5 225 245 252 252 251.5 252 248.0 250 250 250 400 150 21 (2) 2 53.0 25.0  0.0 75 190 37.3 225 245 252 252 251.5 252 248.0 450 450 540 500 150 21 (2) 3 25.5 15.0  0.0 75 190 27.0 225 245 252 252 251.5 252 248.0 250 250 250 350 150 21 (2) 4 52.2 12.8 12.6 75 190 22.6 225 245 252 252 251.5 245 245.0 250 250 250 350 150 21 (2) 5 52.2 75 190 225 245 252 252 251.5 245 245.0 250 250 250 350 150 21 (2) 6 52.2 75 190 225 245 252 252 251.5 245 245.0 250 250 250 350 150 21 (2) 7 52.2 75 190 225 245 252 252 251.5 245 245.0 250 250 250 350 150 21 (2)

[0066] Non-limiting examples of polymer resins that can be employed with the embodiment of FIG. 2 are shown in Table 2, below. TABLE 2 Starting Melt Melt Sample Grade Number Flow MWD Temp. C. wt. 1 WRD5-1561/LR-10207-80-A 1.5 Broad 260 50 lbs. 2 WDR5-1562/LR-10207-80-B 6 Medium 250 50 lbs. 3 WRD5-1563/LR-10207-80-C 10 Narrow 245 50 lbs. 4 WRD5-1554/LR-10207-80-D 3.5 Broad 250 50 lbs. 5 WRD5-1565/LR-10207-80-E 10 Broad 245 50 lbs. 6 WRD5-1566/LR-10207-80-F 10 Broad 245 50 lbs.

[0067] Still referring to Table 2, the resin employed therein for manufacture of the semi-crystalline fiber of the subject invention may have the following composition:

[0068] 3-7 ppm (parts-per-million) magnesium, preferably under 5 ppm.

[0069] 1-5 weight percent TiO₂ or polytetraflouroethylene, preferably 1 weight percent.

[0070] 30-50 ppm aluminum, preferably under 42 ppm.

[0071] 20-50 ppm chlorine, preferably under 24 ppm.

[0072] Under 600 ppm calcium stearate.

[0073] 0.02 to 1.00 weight percent Irganox 1010 (antioxidant manufactured by Rhom Haas), preferably under 0.03 weight percent.

[0074] 400 to 500 ppm Irgafos 168 manufactured by I.C.I., preferably 400 ppm

[0075] MFI (melt flow index) of 0.1 to 1,000, preferably under 10.

[0076] 1 to 10 weight percent Xyllene, preferably under 2 weight percent.

[0077] 1 to 10 weight percent Decalin Soluble, preferably under 2 percent weight.

[0078] 0.1 to 10.0 weight percent CH B (discoloration preventative manufactured by Geigy Industrial Chemical Corp.), preferably under 0.3 percent weight

[0079] 1 to 5 weight percent DSI (an anti-static agent manufactured by Freeman Chemical Corp.), preferably 2.5 weight percent

[0080] Outgassing to 1-50 ppm, preferably under 15 ppm

[0081] Drawing conditions for selected resins of Table 2 employing the protocol of FIG. 2 are shown in Table 3, below. TABLE 3 Rollstands Ovens Rollstands Speed Rollstands (° F.) Factor (fpm) Takeup Sample 1 1 300 1 5 Use Leesona 959 2 299 6 34 Tension 15 3 296 6.1 34 Gage 2 4 6.2 35 Sample 3 1 293 1 5 Use Leesona 959 2 293 8 46 Tension 15 3 301 9 52 Gage 2 4 10 58 Sample 6 1 293 1 5 Use Lessona 959 2 292 9 51 Tension 15 3 288 11 63 Gage 2 4 11.5 63

[0082] Next referring to Table 4 the three fiber samples of Table 3 provided tensile strength data for the drawing conditions of Table 3. As Table 4 shows, the fibers of the present invention exhibited tensile strength as high as 14 g/denier and percent elongation as low as 6; both values being substantially better than those for polymer and glass fibers manufactured with prior art systems. TABLE 4 Tenacity Tensile Energy Linear Max at strain at at Max Density Load Maximum Maximum Modulus Load (den) (gf) (gf/den) (%) (gf/den) (gf-mm) 1 12.00 167.52 13.96 16.7 136.13 4477.96 2 12.00 167.42 13.95 16.7 131.59 4530.95 3 12.00 169.01 14.08 16.7 147.74 4574.25 Mean 12.00 167.98 14.00 16.7 138.49 4527.72 S.D. 0.00 0.89 0.07 0.0 8.33 48.22 C.V. 0.00 0.53 0.53 0.0 6.02 1.07 inimu 12.00 167.42 13.95 16.7 131.59 4477.96 aximu 12.00 169.01 14.08 16.7 147.74 4574.25 1 10.00 110.57 11.06 18.3 112.40 3323.90 2 10.00 89.52 8.95 11.7 87.54 1557.03 3 12.00 96.27 8.02 13.3 71.52 1928.63 Mean 10.67 98.79 9.34 14.4 90.49 2269.85 S.D. 1.15 10.75 1.55 3.5 20.60 931.55 C.V. 10.83 10.88 16.64 24.0 22.76 41.04 inimu 10.00 89.52 8.02 11.7 71.52 1557.03 aximu 12.00 110.57 11.06 18.3 112.40 3323.90 1 12.00 114.86 9.57 6.7 167.74 1150.06 2 9.00 114.23 12.69 6.7 176.86 1081.01 3 9.00 130.84 14.54 8.3 240.54 1628.25 Mean 10.00 119.98 12.27 7.2 195.05 1286.44 S.D. 1.73 9.42 2.51 1.0 39.66 298.02 C.V. 17.32 7.85 20.46 13.3 20.33 23.17 inimu 9.00 114.23 9.57 6.7 167.74 1081.01 aximu 12.00 130.84 14.54 8.3 240.54 1628.25

[0083] Fiber produced by the method of the present invention was assessed for optical transmissivity based on the following protocol. An approximately 50 cm.length of fiber having 10 an outer diameter of 710 micrometers was employed. The light sources used were an Ando model AQ-4303B white light source, an Ando model number AQ-4139 1310 nm laser source and an Ando model number AQ-4147 850 nm laser source. An Ando model number AQ-631 OB optical spectrum analyzer and an Ando model number AQ-1125 power meter with Ando model number AQ-1950 and AQ-1951 heads were also used.

[0084] Initially, the fiber was analyzed without any fiber end preparation. The white light source was first directly coupled to the spectrum analyzer to obtain a reference graph. The fiber of the present invention was then inserted and measured. Subtraction of the reference graph from the resulting fiber graph is shown in FIG. 4. Vertical lines in FIG. 4 show attenuation values of 9.6 dB at 850 nm and 19.5 dB at 1310 nm, both important telecommunication wavelengths.

[0085] Next, the ends of the fiber were polished, and the above described laser light sources and power meter were employed for more accurate attenuation measurements. First, the laser light sources were directly coupled to the power meter by a lass fiber to obtain reference data.

[0086] Next, the fiber of the present invention was inserted in place of the glass fiber.

[0087] Subtraction of the reference data from the resulting fiber data. For the 850 nm wavelength, the fiber attenuation was 3.7 dB (−3.8 dBm (reference)—7. d Bm (fiber)). For the 1310 nm wavelength, the fiber attenuation was 10.88 dB (−3.3 dBm (reference)—14.18 dBm (fiber)).

[0088] Finally, the first white light analysis was repeated with fiber of the present invention having polished ends. FIGS. 5-7 show the attenuation results. FIG. 5 shows attenuation marked at both 850 nm and 1310 nm with vertical lines. FIG. 6 is a close-up of the 850 nm attenuation of FIG. 5. FIG. 7 is a close-up of the 1310 nm attenuation of FIG. 5.

[0089] Next, fiber produced by the method of the present invention was compared to other fibers for optical transmissivity. A 2500 Optical Fiber Analysis System manufactured by Netest, Inc. was used for all tests. Light wavelengths from 600 nm to 1600 nm were passed through the fibers. The 2500 Optical Fiber Analysis System provided light transmissivity values in dB. Tables 5-15 show the light transmissivity values (in dB) for wavelengths from 600 to 1600 nm for, respectively. 62.5 μm glass optical fiber (Table 5); a 390 mm length of 750 μm Mitsubishi optical fiber (Table 6); a 390 nm length of 750 μm Mitsubishi optical fiber employing the overfillmnode of the 2500 Optical Fiber Analysis System (Table 7); a 390 mm length of 1000 un Mitsubishi optical fiber (Table 8); a 390 mm length of the optical fiber of the subject invention (Table 9); a 390 mm length of the semi-crystalline optical fiber of the subject invention employing the restricted mode of the 2500 Optical Fiber Analysis System (Table 10); a re-test of the Table 10 example (Table 11); a 390 mm length of the semi-crystalline optical fiber of the subject invention employing the overfill mode of the 2500 Optical Fiber Analysis System (Table 12); a 390 mm length of 0.40 mm semi-crystalline fiber manufactured by Stem, Inc. (Table 13); a 390 mm length of 0.87 nm semi-crystalline fiber manufactured by South Bend, Inc. (Table 14); and a re-test of the Table 14 example (Table 15). TABLE 5 (nm) dB (nm) dB (nm) dB (nm) dB 600 0.043 860 −0.005 1120 0.004 1380 0.001 610 0.036 870 −0.004 1130 0.005 1390 0.003 620 0.030 880 −0.007 1140 0.004 1400 0.001 630 0.027 890 0.002 1150 0.000 1410 0.004 640 0.024 900 −0.009 1160 0.001 1420 0.004 650 0.022 910 0.002 1170 0.001 1430 0.002 660 0.002 920 −0.005 1180 0.005 1440 0.001 670 0.020 930 −0.003 1190 0.002 1450 0.001 680 0.019 940 −0.004 1200 0.003 1460 0.002 690 0.008 950 −0.005 1210 −0.003 1470 0.006 700 0.009 960 −0.004 1220 0.005 1480 0.003 710 0.006 970 −0.007 1230 0.006 1490 0.004 720 0.006 980 0.006 1240 −0.002 1500 0.002 730 0.006 990 0.006 1250 −0.001 1510 −0.001 740 0.003 1000 0.003 1260 0.001 1520 −0.001 750 0.005 1010 0.001 1270 0.002 1530 0.003 760 0.001 1020 0.005 1280 0.006 1540 0.004 770 0.001 1030 0.005 1290 0.004 1550 0.005 780 −0.004 1040 0.007 1300 0.000 1560 0.004 790 −0.003 1050 −0.001 1310 0.001 1570 0.005 800 −0.003 1060 0.005 1320 0.003 1580 0.003 810 −0.003 1070 0.004 1330 0.004 1590 0.004 820 −0.001 1080 −0.001 1340 0.004 1600 −0.001 830 −0.005 1090 0.004 1350 0.005 840 −0.003 1100 −0.003 1360 0.001 850 −0.005 1110 0.000 1370 0.002

[0090] TABLE 6 (nm) dB (nm) dB (nm) dB (nm) dB 600 9.653 860 12.939 1120 36.183 1380 52.187 610 9.670 870 14.637  1130* 49.850 1390 51.206 620 9.736 880 16.530  1140* 51.230 1400 49.546 630 9.757 890 21.636  1150* 51.787 1410 48.580 640 9.705 900 22.855  1160* 52.027 1420 47.288 650 9.709 910 19.023  1170* 52.589 1430 46.482 660 9.726 920 15.504  1180* 52.791 1440 46.280 670 9.778 930 13.474  1190* 52.094 1450 45.967 680 9.926 940 12.555  1200* 50.873 1460 46.420 690 9.926 950 12.635  1210* 46.906 1470 47.327 700 9.997 960 13.529 1220 37.395 1480 48.225 710 10.891 970 14.878 1230 31.794 1490 49.126 720 11.307 980 19.763 1240 28.213 1500 49.070 730 11.826 990 21.971 1250 25.444 1510 47.731 740 11.710 1000 24.198 1260 23.784 1520 45.981 750 11.218 1010 24.064 1270 23.439 1530 45.159 760 10.915 1020 22.788 1280 23.367 1540 45.879 770 10.858 1030 22.217 1290 23.818 1550 47.166 780 10.842 1040 21.274 1300 24.745 1560 49.660 790 11.097 1050 19.048 1310 26.557 1570 53.145 800 11.309 1060 18.157 1320 30.705 1580 54.326 810 11.375 1070 17.160 1330 42.133 1590 52.994 820 11.346 1080 16.933  1340* 51.076 1600 53.190 830 11.308 1090 17.679  1350* 52.223 840 11.442 1100 19.569  1360* 52.356 850 11.868 1110 26.225  1370* 53.068

[0091] TABLE 7 (nm) dB (nm) dB (nm) dB (nm) dB 600 13.185 860 16.547 1120 38.302 1380 50.373 610 13.284 870 18.277 1130 49.547 1390 50.526 620 13.377 880 20.969 1140 50.583 1400 50.187 630 13.424 890 25.402 1150 51.112 1410 49.687 640 13.417 900 26.316 1160 51.587 1420 49.143 650 13.443 910 22.574 1170 51.923 1430 48.707 660 13.497 920 18.897 1180 51.901 1440 48.454 670 13.576 930 16.972 1190 51.447 1450 48.472 680 13.742 940 16.180 1200 50.783 1460 48.809 690 13.797 950 16.310 1210 46.332 1470 49.437 700 13.891 960 17.174 1220 39.306 1480 50.362 710 14.113 970 18.554 1230 34.122 1490 50.929 720 14.557 980 22.844 1240 30.902 1500 50.813 730 15.021 990 25.065 1250 28.144 1510 49.505 740 14.928 1000 27.014 1260 26.744 1520 48.227 750 14.497 1010 26.788 1270 26.378 1530 47.660 760 14.235 1020 25.712 1280 26.461 1540 48.127 770 14.202 1030 25.210 1290 26.982 1550 49.52? 780 14.333 1040 23.925 1300 27.931 1560 51.57? 790 14.575 1050 22.073 1310 29.901 1570 53.019 800 14.786 1060 21.122 1320 34.052 1580 53.479 810 14.858 1070 20.200 1300 43.172 1590 53.508 820 14.863 1080 20.035 1340 49.178 1600 53.042 830 14.857 1090 20.808 1350 49.163 840 15.005 1100 22.955 1360 49.287 850 15.501 1110 28.954 1370 49.824

[0092] TABLE 8 (nm) dB (nm) dB (nm) dB (nm) dB 600 12.629 860 15.802 1120 38.558 1380 54.799 610 12.671 870 16.763  1130* 52.374 1390 53.274 620 12.720 880 19.316  1140* 53.623 1400 51.769 630 12.747 890 24.411  1150* 53.248 1410 50.822 640 12.686 900 25.787  1160* 54.627 1420 49.575 650 12.695 910 22.089  1170* 55.801 1430 49.141 660 12.706 920 17.781  1180* 54.909 1440 48.976 670 12.760 930 16.409  1190* 54.460 1450 48.563 680 12.751 940 15.502  1200* 53.748 1460 49.238 690 12.773 950 15.575  1210* 49.565 1470 49.329 700 12.847 960 16.511 1220 39.981 1480 50.800 710 13.024 970 17.839 1230 34.452 1490 52.058 720 13.431 980 22.523 1240 30.977 1500 52.202 730 13.963 990 24.717 1250 28.272 1510 50.357 740 13.891 1000 26.897 1260 26.607 1520 48.722 750 13.399 1010 26.852 1270 26.256 1530 48.033 760 13.808 1020 25.542 1280 26.284 1540 48.689 770 13.748 1030 25.092 1290 26.748 1550 50.001 780 13.731 1040 24.195 1300 27.673 1560 52.540 790 13.987 1050 21.934 1310 29.447 1570 55.611 800 14.216 1060 21.040 1320 33.506 1580 58.537 810 14.292 1070 20.028 1330 44.486 1590 58.610 820 14.262 1080 19.773  1340* 52.828 1600 57.155 830 14.233 1090 20.471  1350* 54.737 840 14.359 1100 22.301  1360* 54.805 850 14.774 1110 28.793  1370* 55.373

[0093] TABLE 9 (nm) dB (nm) dB (nm) dB (nm) dB 600 10.381 860 13.713 1120 36.124 1380 100.000 610 10.406 870 15.428  1130* 49.603 1390 66.298 620 10.486 880 17.358  1140* 50.821 1400 69.706 630 10.515 890 22.528  1150* 51.282 1410 56.471 640 10.477 900 23.733  1160* 51.824 1420 64.875 650 10.486 910 19.890  1170* 52.409 1430 61.195 660 10.502 920 16.278  1180* 52.229 1440 61.173 670 10.560 930 14.237  1190* 51.870 1450 58.226 680 10.576 940 13.348  1200* 51.269 1460 58.376 690 10.605 950 13.482  1210* 46.580 1470 63.069 700 10.680 960 14.474 1220 36.992 1480 100.000 710 10.864 970 15.841 1230 31.541 1490 100.000 720 11.283 980 19.738 1240 28.047 1500 100.000 730 11.818 990 21.897 1250 25.301 1510 100.000 740 12.449 1000 24.073 1260 23.688 1520 100.000 750 11.949 1010 23.917 1270 23.327 1530 73.387 760 11.638 1020 22.597 1280 23.372 1540 56.705 770 11.588 1030 22.152 1290 23.857 1550 60.803 780 11.577 1040 21.191 1300 24.809 1560 100.000 790 11.834 1050 18.951 1310 26.646 1570 100.000 800 12.059 1060 18.037 1320 30.863 1580 100.000 810 12.126 1070 17.021 1330 42.283 1590 62.133 820 12.102 1080 16.791  1340* 50.471 1600 67.620 830 12.083 1090 17.505  1350* 50.933 840 12.225 1100 19.422  1360* 51.943 850 12.657 1110 26.089  1370* 53.052

[0094] TABLE 10 (nm) dB (nm) dB (nm) dB (nm) dB 600 8.774 890 19.719  1180* 50.437 1470 44.398 610 8.781 900 20.948  1190* 49.714 1480 45.387 620 8.817 910 17.129  1200* 48.895 1490 46.535 630 8.763 920 13.537 1210 44.677 1500 46.814 640 8.705 930 11.506 1220 35.174 1510 45.806 650 8.639 940 10.623 1230 29.607 1520 44.834 660 8.641 950 10.757 1240 26.079 1530 44.156 670 8.642 960 11.797 1250 23.382 1540 44.316 680 8.630 970 13.159 1260 21.769 1550 46.065 690 9.340 980 18.509 1270 21.396 1560 47.567 700 9.385 990 20.578 1280 21.430 1570 49.000 710 9.528 1000  22.655 1290 21.904 1580 49.604 720 9.925 1010  22.454 1300 22.841 1590 50.594 730 10.427 1020  21.089 1310 24.669 1600 50.383 740 10.321 1030  20.612 1320 28.871 1610 48.200 750 9.810 1040  19.607 1330 40.369 1620 46.552 760 9.456 1050  17.354  1340* 47.805 1630 44.963 770 9.368 1060  16.428  1350* 48.403 1640 42.440 780 9.435 1070  15.401  1360* 49.780 1650 39.513 790 9.528 1080  15.152  1370* 49.881 1660 36.347 800 9.715 1090  15.839  1380* 49.464 1670 33.743 810 9.757 1100  17.729  1390* 48.338 1680 31.170 820 9.699 1110  24.290  1400* 46.343 1690 28.274 830 9.643 1120  34.236  1410* 45.010 1700 25.575 840 9.757 1130* 47.850  1420* 44.113 1710 23.906 850 10.145 1140* 48.804 1430 43.374 1720 22.672 860 11.147 1150* 49.823 1440 43.019 1730 21.781 870 12.791 1160* 50.674 1450 42.877 1740 21.028 880 15.378 1170* 50.694 1460 43.518 1750 20.876

[0095] TABLE 11 (nm) dB (nm) dB (nm) dB (nm) dB 600 8.842 890 19.778  1180* 50.487 1470 44.163 610 8.844 900 21.001  1190* 49.325 1480 45.399 620 8.895 910 17.171  1200* 49.269 1490 46.504 630 8.834 920 13.584  1210* 44.796 1500 47.308 640 8.775 930 11.554 1220 35.128 1510 46.253 650 8.713 940 10.670 1230 29.623 1520 44.695 660 8.715 950 10.802 1240 26.117 1530 44.003 670 8.712 960 11.835 1250 23.418 1540 44.372 680 8.689 970 13.203 1260 21.801 1550 45.225 690 9.397 980 18.539 1270 21.426 1560 47.746 700 9.437 990 20.618 1280 21.459 1570 49.846 710 9.588 1000  22.696 1290 21.931 1580 52.131 720 9.979 1010  22.499 1300 22.869 1590 49.697 730 10.480 1020  21.130 1310 24.689 1600 50.017 740 10.378 1030  20.661 1320 28.895 1610 48.099 750 9.864 1040  19.655 1330 40.207 1620 47.789 760 9.511 1050  17.399  1340* 48.274 1630 45.442 770 9.420 1060  16.470  1350* 48.161 1640 42.262 780 9.491 1070  15.446  1360* 49.510 1650 39.443 790 9.582 1080  15.198  1370* 50.007 1660 36.444 800 9.769 1090  15.882  1380* 49.489 1670 33.776 810 9.811 1100  17.771  1390* 48.667 1680 31.205 820 9.752 1110  24.334  1400* 46.397 1690 28.315 830 9.698 1120  34.298  1410* 44.995 1700 25.745 840 9.812 1130* 48.105  1420* 43.993 1710 23.890 850 10.198 1140* 48.903 1430 43.481 1720 22.747 860 11.203 1150* 49.750  1140* 43.126 1730 21.823 870 12.848 1160* 50.283 1450 42.946 1740 21.117 880 15.432 1170* 50.295  1460* 43.454 1750 20.854

[0096] TABLE 12 (nm) dB (nm) dB (nm) dB (nm) dB 600 −5.337  890 6.285 1180 34.527 1470 28.480 610 −5.219  900 7.104 1190 34.051 1480 29.817 620 −5.128  910 3.466 1200 33.361 1490 31.074 630 −5.082  920 −0.191 1210 28.392 1500 32.010 640 −5.105  930 −2.048 1220 21.332 1510 31.852 650 −5.100  940 −2.798 1230 16.315 1520 31.227 660 −5.086  950 −2.546 1240 13.216 1530 30.801 670 −5.044  960 −1.528 1250 10.566 1540 31.082 680 −5.026  970 −0.113 1260 9.208 1550 32.165 690 −4.873  980 5.426 1270 8.852 1560 33.794 700 −4.791  990 7.565 1280 8.918 1570 35.159 710 −4.578 1000 9.432 1290 9.458 1580 35.596 720 −4.138 1010 9.160 1300 10.444 1590 35.471 730 −3.684 1020 8.061 1310 12.442 1600 35.000 740 −3.788 1030 7.527 1320 16.621 1610 34.083 750 −4.228 1040 6.224 1330 25.734 1620 32.850 760 −4.511 1050 4.348 1340 32.038 1630 31.360 770 −4.562 1060 3.383 1350 32.876 1640 29.434 780 −4.563 1070 2.475 1360 33.594 1650 27.083 790 −4.318 1080 2.323 1370 34.212 1660 24.387 800 −4.121 1090 3.128 1380 33.824 1670 21.959 810 −4.059 1100 5.301 1390 32.602 1680 19.552 820 −4.041 1110 11.301 1400 30.827 1690 16.856 830 −4.068 1120 20.617 1410 29.406 1700 14.300 840 −3.922 1130 31.783 1420 28.317 1710 12.590 850 −3.444 1140 32.959 1430 27.606 1720 11.334 860 −2.401 1150 33.651 1440 27.220 1730 10.415 870 −0.691 1160 34.237 1450 27.192 1740 9.701 880 1.974 1170 34.593 1460 27.618 1750 9.340

[0097] TABLE 13 (nm) dB (nm) dB (nm) dB (nm) dB 600* 62.255  860* 100.000 1120* 100.000 1380* 100.000 610* 100.000  870* 59.091 1130* 100.000 1390* 66.298 620* 47.328  880* 100.000 1140* 60.253 1400* 69.706 630* 57.769  890* 100.000 1150* 59.477 1410* 56.471 640* 51.761  900* 61.301 1160* 61.202 1420* 64.875 650* 100.000  910* 60.821 1170* 61.934 1430* 61.195 660* 50.556  920* 54.693 1180* 60.940 1440* 61.173 670* 56.721  930* 57.117 1190* 100.000 1450* 58.226 680* 100.000  940* 60.572 1200* 61.949 1460* 58.376 690* 63.770  950* 56.965 1210* 64.255 1470* 63.039 700* 100.000  960* 61.624 1220* 63.147 1480* 100.000 710* 64.007  970* 100.000 1230* 64.532 1490* 100.000 720* 55.631  980* 60.502 1240* 65.634 1500* 100.000 730* 100.000  990* 62.316 1250* 61.977 1510* 100.000 740* 100.000 1000* 100.000 1260* 59.644 1520* 100.000 750* 60.805 1010* 100.000 1270* 59.936 1530* 73.387 760* 100.000 1020* 63.868 1280* 57.734 1540* 56.705 770* 100.000 1030* 62.990 1290* 61.049 1550* 60.803 780* 100.000 1040* 60.415 1300* 100.000 1560* 100.000 790* 63.502 1050* 100.000 1310* 70.399 1570* 100.000 800* 58.857 1060* 69.162 1320* 58.090 1580* 100.000 810* 75.356 1070* 100.000 1330* 67.198 1590* 62.133 820* 57.289 1080* 64.076 1340* 59.067 1600* 67.620 830* 100.000 1090* 60.938 1350* 100.000 840* 100.000 1100* 100.000 1360* 67.702 850* 100.000 1110* 58.979 1370* 100.000

[0098] TABLE 14 (nm) dB (nm) dB (nm) dB (nm) dB 600* 47.386  860* 57.702 1120* 57.180 1380* 60.461 610* 100.000  870* 55.810 1130* 59.590 1390* 66.785 620* 100.000  880* 58.310 1140* 63.530 1400* 61.388 630* 46.934  890* 63.055 1150* 64.065 1410* 100.000 640* 48.358  900* 57.220 1160* 70.487 1420* 61.483 650* 47.695  910* 100.000 1170* 100.000 1430* 63.979 660* 100.000  920* 100.000 1180* 64.619 1440* 60.596 670* 100.000  930* 100.000 1190* 64.591 1450* 61.274 680* 50.241  940* 100.000 1200* 100.000 1460* 67.941 690* 58.952  950* 55.660 1210* 64.554 1470* 58.440 700* 100.000  960* 53.755 1220* 64.545 1480* 100.000 710* 53.527  970* 53.440 1230* 63.703 1490* 100.000 720* 56.022  980* 58.719 1240* 60.679 1500* 57.345 730* 55.009  990* 56.909 1250* 65.525 1510* 68.865 740* 56.680 1000* 100.000 1260* 65.501 1520* 65.305 750* 59.446 1010* 65.181 1270* 100.000 1530* 60.674 760* 55.141 1020* 63.892 1280* 63.028 1540* 60.979 770* 61.179 1030* 61.046 1290* 60.686 1550* 64.194 780* 65.462 1040* 63.602 1300* 62.908 1560* 100.000 790* 56.345 1050* 100.000 1310* 100.000 1570* 100.000 800* 54.962 1060* 100.000 1320* 100.000 1580* 58.337 810* 100.000 1070* 61.379 1330* 64.271 1590* 100.000 820* 59.622 1080* 60.786 1340* 60.931 1600* 61.698 830* 57.904 1090* 60.456 1350* 100.000 840* 62.566 1100* 57.701 1360* 73.630 850* 55.194 1110* 56.981 1370* 61.903

[0099] TABLE 15 (nm) dB (nm) dB (nm) dB (nm) dB 600* 100.000  860* 53.722 1120* 59.880 1380* 60.885 610* 100.000  870* 54.951 1130* 62.199 1390* 100.000 620* 50.427  880* 53.620 1140* 64.085 1400* 100.000 630* 46.451  890* 60.045 1150* 64.065 1410* 62.529 640* 52.337  900* 58.050 1160* 100.000 1420* 100.000 650* 50.126  910* 57.288 1170* 60.911 1430* 63.744 660* 100.000  920* 63.294 1180* 100.000 1440* 61.192 670* 55.359  930* 100.000 1190* 63.065 1450* 60.548 680* 49.226  940* 57.637 1200* 62.588 1460* 64.631 690* 46.164  950* 55.436 1210* 61.321 1470* 66.751 700* 54.803  960* 53.292 1220* 100.000 1480* 59.763 710* 100.000  970* 55.574 1230* 71.299 1490* 64.960 720* 100.000  980* 58.215 1240* 61.625 1500* 100.000 730* 51.524  990* 57.550 1250* 63.861 1510* 100.000 740* 100.000 1000* 61.161 1260* 66.470 1520* 61.570 750* 100.000 1010* 61.781 1270* 77.228 1530* 100.000 760* 54.471 1020* 63.699 1280* 66.038 1540* 60.010 770* 55.159 1030* 61.046 1290* 100.000 1550* 60.710 780* 100.000 1040* 64.394 1300* 64.048 1560* 59.641 790* 57.436 1050* 60.241 1310* 60.854 1570* 66.068 800* 69.276 1060* 65.937 1320* 67.366 1580* 100.000 810* 62.692 1070* 64.389 1330* 61.383 1590* 68.815 820* 55.412 1080* 69.632 1340* 67.698 1600* 100.000 830* 55.023 1090* 59.887 1350* 61.919 840* 56.545 1100* 61.567 1360* 100.000 850* 54.599 1110* 58.704 1370* 73.806

[0100] First referring to Table 5, the 62.5 μm glass optical fiber was used as a standard, showing light transmissivity across the 600 to 1600 nm spectrum. Comparing Tables 6, 7 and 8 with Tables 9, 10, 11 and 12 shows that the semi-crystalline optical fiber of the present invention is light tranmissive at comparable wavelengths in comparable amounts to known amorphous optical fibers, including, but not limited to the 850 nm and 1310 nm wavelengths. At 850 nm, the known amorphous optical fibers had values of 11.868 dB, 15.501 dB and 14.774 dB while the semi-crystalline optical fiber of the present invention had values of 12.657 dB, 10.145 dB, 10.198 dB and 3.444 dB. Likewise, at 1310 nm the known amorphous optical fibers had values of 26.557 dB, 29.901 dB and 29.447 dB while the semi-crystalline optical fiber of the present invention had values of 26.646 dB, 24.669 dB, 24.689 dB and 12.442 dB.

[0101] Comparing the semi-crystalline optical fiber of the present invention (Tables 9, 10, 11and 12) to known semi-crystalline fibers (Tables 13, 14 and 15) shows that the known semi-crystalline polyethylene fibers pass essentially no light of measurable quantities at any wavelength, and specifically not at 850 nm and 1310 nm. At 850 nm, the known semi-crystalline fibers have values of 100.000 dB, 55.194 dB, and 54.599 dB, while at 1310 nm the values are 70.399 dB, 100.00 dB and 60.038 dB. Unlike the semi-crystalline fibers of the present invention of Tables 9, 10 and 11, the known semi-crystalline polyethylene fibers of Tables 13, 14 and 15 are useless as light conduits. 

1. An apparatus for producing optical fibers, comprising: an extruder for heating polymer resin to produce molten polymer and for supplying the molten polymer at a constant pressure; a gear pump in fluid communication with the extruder for receiving the molten polymer and for controlling the polymer flow rate; a spinneret in fluid communication with the gear pump for spinning the molten polymer into the optical fibers; and a heat source for controlling the temperature of the optical fibers after the fibers exit the spinneret, wherein the temperature-controlling maximizes crystallization of the molten polymer.
 2. The apparatus of claim 1, wherein the heat source comprises a plurality of vertically-aligned temperature zones, each zone having a temperature lower than the zone directly above.
 3. The apparatus of claim 2, wherein the temperature of the optical fibers exiting the bottommost temperature zone is near room temperature.
 4. The apparatus of claim 1, further comprising a take-up roller for tensioning the optical fibers after the fibers exit the spinneret.
 5. The apparatus of claim 4, further comprising at least one drawing station to draw the optical fibers after the fibers have been tensioned and temperature-controlled.
 6. The apparatus of claim 5, further comprising an annealing station to anneal the optical fibers after the fibers have been drawn.
 7. An apparatus for producing optical fibers, comprising: an extruder for heating polymer resin to produce molten polymer and for supplying the molten polymer at a constant pressure; a gear pump in fluid communication with the extruder for receiving the molten polymer and for controlling the polymer flow rate; a spinneret in fluid communication with the gear pump for spinning the molten polymer into the optical fibers; and a take-up roller for tensioning the optical fibers after the fibers exit the spinneret, wherein the tensioning of the optical fibers maximizes crystallization of the molten polymer.
 8. The apparatus of claim 7, further comprising a heater for controlling the temperature of the optical fibers after the fibers exit the spinneret.
 9. The apparatus of claim 8, further comprising at least one drawing station to draw the optical fibers after the fibers have been tensioned and temperature-controlled.
 10. The apparatus of claim 9, further comprising an annealing station to anneal the optical fibers after the fibers have been drawn.
 11. The apparatus of claim 8, wherein the heater comprises a plurality of vertically-aligned temperature zones, each zone having a temperature lower than the zone directly above.
 12. The apparatus of claim 11, wherein the temperature of the optical fibers exiting the bottommost temperature zone is near room temperature.
 13. The apparatus of claim 7, further comprising at least one drawing station to draw the optical fibers after the fibers have been tensioned.
 14. The apparatus of claim 13, further comprising an annealing station to anneal the optical fibers after the fibers have been drawn.
 15. An apparatus for producing optical fibers, comprising: an extruder for heating polymer resin to produce molten polymer and for supplying the molten polymer at a constant pressure; a gear pump in fluid communication with the extruder for receiving the molten polymer and for controlling the polymer flow rate; a spinneret in fluid communication with the gear pump for spinning the molten polymer into the optical fibers; a heat source for controlling the temperature of the optical fibers after the fibers exit the spinneret; and a take-up roller for tensioning the optical fibers after the fibers exit the spinneret, wherein the temperature-controlling and the tensioning of the optical fibers maximize crystallization of the molten polymer.
 16. The apparatus of claim 15, wherein the heat source comprises a plurality of vertically-aligned temperature zones, each zone having a temperature lower than the zone directly above.
 17. The apparatus of claim 16, wherein the temperature of the optical fibers exiting the bottommost temperature zone is near room temperature.
 18. The apparatus of claim 15, further comprising at least one drawing station to draw the optical fibers after the fibers have been tensioned and temperature-controlled.
 19. The apparatus of claim 18, further comprising an annealing station to anneal the optical fibers after the fibers have been drawn.
 20. A method for producing optical fibers, comprising: heating polymer resin to produce molten polymer; spinning in a spinneret the molten polymer into the optical fibers; and controlling the temperature of the optical fibers after the fibers exit the spinneret, wherein the temperature-controlling maximizes crystallization of the molten polymer.
 21. The method of claim 20, further comprising controlling the molten polymer flow rate before spinning.
 22. The method of claim 20, wherein the temperature-controlling comprises controlling the temperature of a plurality of vertically-aligned temperature zones through which the optical fibers travel, each zone having a temperature lower than the zone directly above.
 23. The method of claim 22, wherein the temperature of the optical fibers exiting the bottommost temperature zone is near room temperature.
 24. The method of claim 20, further comprising tensioning the optical fibers after the fibers exit the spinneret.
 25. The method of claim 24, further comprising drawing the optical fibers.
 26. The method of claim 25, further comprising annealing the drawn optical fibers.
 27. A method for producing optical fibers, comprising: heating polymer resin to produce molten polymer; spinning in a spinneret the molten polymer into the optical fibers; and tensioning the optical fibers after the fibers exit the spinneret, wherein the tensioning maximizes crystallization of the molten polymer.
 28. The method of claim 27, further comprising controlling the molten polymer flow rate before spinning.
 29. The method of claim 27, further comprising controlling the temperature of the optical fibers after the fibers exit the spinneret.
 30. The method of claim 29, further comprising drawing the optical fibers.
 31. The method of claim 30, further comprising annealing the drawn optical fibers.
 32. The method of claim 29, wherein the temperature-controlling comprises controlling the temperature of a plurality of vertically-aligned temperature zones through which the optical fibers travel, each zone having a temperature lower than the zone directly above.
 33. The method of claim 32, wherein the temperature of the optical fibers exiting the bottommost temperature zone is near room temperature.
 34. The method of claim 27, further comprising drawing the optical fibers.
 35. The method of claim 34, further comprising annealing the drawn optical fibers.
 36. A method for producing optical fibers, comprising: heating polymer resin to produce molten polymer; spinning in a spinneret the molten polymer into the optical fibers; controlling the temperature of the optical fibers after the fibers exit the spinneret; and tensioning the optical fibers after the fibers exit the spinneret, wherein the temperature-controlling and tensioning maximize crystallization of the molten polymer.
 37. The method of claim 36, further comprising controlling the molten polymer flow rate before spinning.
 38. The method of claim 36, wherein the temperature-controlling comprises controlling the temperature of a plurality of vertically-aligned temperature zones through which the optical fibers travel, each zone having a temperature lower than the zone directly above.
 39. The method of claim 38, wherein the temperature of the optical fibers exiting the bottommost temperature zone is near room temperature.
 40. The method of claim 36, further comprising drawing the optical fibers.
 41. The method of claim 40, further comprising annealing the drawn optical fibers.
 42. An optical fiber comprising: polymer resin heated to produce molten polymer, the molten polymer being spun in a spinneret into the optical fiber, wherein the temperature of the optical fiber is controlled after the fiber exits the spinneret, such that crystallization of the molten polymer is maximized.
 43. The optical fiber of claim 42, wherein the molten polymer flow rate is controlled before the molten polymer is spun.
 44. The optical fiber of claim 42, wherein the temperature is controlled using a plurality of vertically-aligned temperature zones through which the optical fiber travels, each zone having a temperature lower than the zone directly above.
 45. The optical fiber of claim 44, wherein the temperature of the optical fiber exiting the bottommost temperature zone is near room temperature.
 46. The optical fiber of claim 42, wherein the optical fiber is tensioned after the fiber exits the spinneret.
 47. The optical fiber of claim 46, wherein the optical fiber is drawn using a drawing station.
 48. The optical fiber of claim 47, wherein the drawn optical fiber is annealed.
 49. An optical fiber comprising: polymer resin heated to produce molten polymer, the molten polymer being spun in a spinneret into the optical fiber, wherein the optical fiber is tensioned after the fiber exits the spinneret, such that crystallization of the molten polymer is maximized.
 50. The optical fiber of claim 49, wherein the molten polymer flow rate is controlled before the molten polymer is spun.
 51. The optical fiber of claim 49, wherein the temperatu re of the optical fiber is controlled after the fiber exits the spinneret.
 52. The optical fiber of claim 51, wherein the optical fiber is drawn using a drawing s tation.
 53. The optical fiber of claim 52, wherein the drawn optical fiber is annealed.
 54. The optical fiber of claim 51, wherein the temperature is controlled using a plurality of vertically-aligned temperature zones through which the optical fiber travels, each zone having a temperature lower than the zone directly above.
 55. The optical fiber of claim 54, wherein the temperature of the optical fiber exiting the bottommost temperature zone is near room temperature.
 56. The optical fiber of claim 49, wherein the optical fiber is drawn using a drawing station.
 57. The optical fiber of claim 56, wherein the drawn optical fiber is annealed.
 58. An optical fiber comprising: polymer resin heated to produce molten polymer, the molten polymer being spun in a spinneret into the optical fiber, wherein the temperature of the optical fiber is controlled and the optical fiber is tensioned after the fiber exits the spinneret, such that crystallization of the molten polymer is maximized.
 59. The optical fiber of claim 58, wherein the molten polymer flow rate is controlled before the molten polymer is spun.
 60. The optical fiber of claim 58, wherein the temperature is controlled using a plurality of vertically-aligned temperature zones through which the optical fiber travels, each zone having a temperature lower than the zone directly above.
 61. The optical fiber of claim 60, wherein the temperature of the optical fiber exiting the bottommost temperature zone is near room temperature.
 62. The optical fiber of claim 58, wherein the optical fiber is drawn using a drawing station.
 63. The optical fiber of claim 62, wherein the drawn optical fiber is annealed. 